Chapter 4 - Fingerprints
Fingerprints
Recording and classifying prints
• Rolling inked prints
• Loops, whorls, arches, ridge characteristics
• Primary identification number
Lifting prints
• Black, white, and fluorescent powder
• Chemicals—ninhydrin, iodine, silver nitrate, cyanoacrylate
Other types of prints
Palm, lip, teeth, eye, ear, voice, shoeprints, and footprints
Fundamental Principles of Fingerprints
1. A fingerprint is an individual characteristic.
2. A fingerprint remains unchanged during an individual’s lifetime.
3. Fingerprints have general characteristic ridge patterns that permit them to be
systematically classified.
4. When do fingerprints form?
 Ridges form in early embryonic development (3rd or 4th month)
 Remain constant throughout life.
5. What determines fingerprint pattern and minutiae?
• DNA: Genes
• Environmental forces: pressures within the womb and contact with the amniotic
fluid
6. What do the genes control?
 The tissue underlying the first few layers of skin is controlled by genes.
 This tissue forms a unique pattern in the skin layer – Dermal Papillae
 Environment has more to do with fingerprints than genes!!
7. John Dillinger –
 Couldn’t change fingerprints with acid
 Can only be altered by deep scarring of dermal layer (2-3mm).
History of Fingerprinting
1. Used in Ancient China as far back as 3 thousand years ago to sign documents.
2. William Herschel (1858)
 India - English civil servant required natives to sign
 contracts with the imprint of right hand
3. Henry Fauld (1870’s)
 Became the first person to solve a crime using fingerprints.
 Matched the fingerprints found on a cup at a robbery in Tokyo with those of a servant.
 First to suggest fingerprinting as the primary means of identification.
4. Francis Galton (1892)
 Fingerprints do not change as you age
 No two are exactly the same.
 Odds of two fingerprints being the same were 1 in 64 billion.
 Published 1st book on Fingerprinting
 Coined terms: loops, arches, and whorls.
5. Sir Edward Henry (1897)
Developed a System to file fingerprints
Fingerprinting in the US
1. NY was the 1st state to use fingerprints – 1901
2. Became the official system of criminal identification in the U.S. in 1924 at the formation
of the F.B.I.
3. US vs. Mitchell (1999)
 Challenged the individuality of fingerprints
 Court ruled Human friction ridges are unique & permanent
History from 1850 to 1900
1. William Herschel—required Indians to put their fingerprints on contracts, and used
fingerprints as a means of identifying prisoners
2. Henry Faulds—claimed that fingerprints did not change over time and that they could be
classified for identification
3. Alphonse Bertillon—proposed body measurements as a means of identification; termed
anthropometry
4. Francis Galton—developed a primary classification scheme based on loops, arches, and
whorls
5. Edward Richard Henry—in collaboration with Galton, instituted a numerical
classification system
6. Juan Vucetich—developed a fingerprint classification system based on Galton’s that is
used in Spanish-speaking countries
Fingerprinting
• Height – Fingerprinting surface should be 39 inches from floor
• Clean fingers with alcohol swab
• The individual should stand to the right and rear of the person taking the fingerprints in
front of the card
Fingerprinting Procedure
1. Thumbs rolled toward the center of the body
2. Fingers rolled away from the center of the body.
3. Roll each finger in the correct space taking care to lift each finger up and away after
rolling, to avoid smudging.
4. Flat Impressions - Taken simultaneously without rolling, at a 45o angle and then the
thumbs.
5. What can go wrong?
 Too dark  Too light –
 Ink unevenly distributed -
Minutiae
Minutiae - characteristics of ridge pattern
 Ridge ending
 Island or short ridge
 Bridge
 Eye or enclosure
 Delta
Ridge Characteristics
Furcations
1. Bifurcation
2. Trifurcation
Endings
1. Ridge Ending
2. Opposed Bifurcation Ridge Ending





Bifurcation or fork
Dot
Spur
Double bifurcation
Trifurcation
3. Double bifurcation
4. Opposed bifurcation
Hook, Dot, Island, & Lake
1. Island (Short Ridge)
2. Dot
3. Lake (enclosure)
4. Hook
Bridge & Ridge Crossings
1. Bridge
2. Ridge Crossing
Arch
1. An arch has friction ridges that enter on one side of the finger and cross to the other side
while rising upward in the middle. They do NOT have type lines, deltas, or cores.
2. Types
• Plain
• Tented
Loop
1. A loop must have one or more ridges entering and exiting from the same side. Loops
must have one delta.
2. Types
 Radial—opens toward the thumb
 Ulnar—opens toward the “pinky” (little finger)
3. Which type of loop is this, if it is on the right hand? Left hand?
Whorl
1. A plain or central pocket whorl has at least one ridge that makes a complete circuit.
2. A double loop is made of two loops. An accidental is a pattern not covered by other
categories.
3. Whorls have at least two deltas and a core.
4. Types
• Plain
• Central pocket
• Double loop
• Accidental
Percentages in the Population
 Loop – 65%
 Whorls – 30%-35%
 Arches – 5%
Core
• Top of the innermost re-curving ridge.
• Center of the pattern
Type Lines
1. Diverging ridges that go above & below the loop
Delta
1. The point of divergence of the type lines
Loop Pattern
1. One or more ridges entering and exiting from the same side it began.
2. Must have one delta.
Types of Loops
1. Radial--opens towards thumb
2. Ulnar--opens towards pinky
Whorl
1. Have type lines and a minimum of 2
deltas
2. Types
• Plain
• Central Pocket
• Double Loop
• Accidental
Plain & Central Pocket loop
1. Both have at least one ridge that makes a complete circuit (spiral).
PLAIN - Line drawn between the two
CENTRAL POCKET LOOP - Line
deltas touches a spiral ridge
drawn between the two deltas doesn’t
touch a spiral ridge
Double loop
1. Two loops combined
2. s-shaped
Accidental
• Has 2 or more patterns (not including
the plain arch)
Arches
1. Ridges enter on one side and cross to the other side while rising upward in the middle.
2. No type lines, deltas, or cores.
3. Types
Tented sharp center rise
Plain
What is the fingerprint pattern?
Which Loop is it?
The Henry System (1899)
1. Classification system using all 10 fingers. Based on identifying the patterns of each
finger.
2. 1,024 labels are created.
3. Still used today.
4. The fingerprint record is filed under its label
5. To locate a record, only 1 / 1,024th of the entire collection must be examined
Step 1: Determine which fingers have whorls
Step 2: Each finger is given a point value
Assign the number of points for each finger that has a whorl and substitute into the equation:
That number is your primary classification number.
Comparison of Prints
1. There are no legal requirements in the United States on the number of points required for
a match.
2. Generally, criminal courts will accept 8 to 12 points of similarity.
Latent Prints
1. Latent fingerprints are those that are not visible to the naked eye. These prints consist of
the natural secretions of human skin and require development for them to become visible
2. Most secretions come from three glands:
• Eccrine—secretes largely water, with both inorganic (ammonia, chlorides, metal
ions, phosphates) and organic (amino acids, lactic acids, urea, sugars) compounds.
Most important for fingerprints.
• Apocrine—secretes pheromones and other organic materials.
• Sebaceous—secretes fatty or greasy substances.
Developing Latent Prints
1. Developing a print requires substances that interact with secretions, causing the print to
stand out against its background. It may be necessary to attempt more than one technique,
done in a particular order so as not to destroy the print.
2. In modern labs and criminal investigations, lasers and alternative light sources are used to
view latent fingerprints. These were first used by the FBI in 1978. Since lasers can
damage the retina of the eye, special precautions must be taken.
3. Powders—adhere to both water and fatty deposits. Choose a color to contrast with
background.
4. Silver nitrate—reacts with chloride to form silver chloride, a material that turns gray
when exposed to light.
5. Ninhydrin—reacts with amino acids to produce a purple color.
6. Silver nitrate—reacts with chloride to form silver chloride, a material that turns gray
when exposed to light.
7. Cyanoacrylate—“superglue” fumes react with water and other fingerprint constituents to
form a hard, whitish deposit.
8. In modern labs and criminal investigations, lasers and alternative light sources are used to
view latent fingerprints. These were first used by the FBI in 1978. Since lasers can
damage the retina of the eye, special precautions must be taken.
Other ways of locating Latent Prints
1. RUVIS - Reflected UV Imaging System
2. UV light is used to locate latent prints
3. Chemicals can also be used
Developing fingerprints using powders
1. Used on hard, non porous surfaces
2. Glass, mirror, metals, painted wood, tile, your desk, etc…
3. Adhere (stick) to water and fatty deposits in prints.
 Use black (charcoal) for light surfaces
 Use gray (aluminum) for dark surfaces
4. Magnetic Powder - special “brush” won’t smudge print (leather, rough plastic). Works
better on shiny surfaces or plastic baggies or containers.
5. Fluorescent Powder - print glows with UV light
Developing Fingerprints Using Iodine
1.
2.
3.
4.
5.
6.
Heating iodine crystal causes sublimation (Liquid to Gas)
Fumes react with oils on skin
Temporary yellow brown print
To last longer spray with starch to set iodine.
Photograph after the treatment – permanent record.
Use on porous surface
Developing Fingerprints using Silver nitrate – Physical developer
1. Amino acids react with chlorides to form silver chloride (gray when exposed to light)
2. Develops prints not developed by other chemicals, even wet or documents over 2000
years old
Developing Fingerprints using Ninhydrin
1.
2.
3.
4.
5.
Reacts with amino acids in sweat to produce a purple print.
Reaction takes 1 to 2 hrs or more on weaker prints.
Heat speeds it up.
Used on paper as old as 15 years old
Preferred method by scientist
Developing Fingerprints using Cyanoacrylate “super glue”
1. For non-porous materials such as metals, electrical tape, leather, plastic bags
2. Heat glue: vapors react with fingerprint constituents to form a hard, whitish print.
New Advances in Fingerprinting
1. DFO- (1,8-diazafluoren-9-one) instead of ninhydrin. 2.5 times more latent print
exposure.
2. Dye Combinations - RAM, RAY, MRM 10 used with Super Glue fuming
Laser Techniques
1. In modern labs and criminal investigations, lasers and alternative light sources are used to
view latent fingerprints.
2. It was first used by the FBI in 1978.
3. Since lasers can damage the retina of the eye, special precautions must be taken and a
filter used.
Other Prints
1.
2.
3.
4.
5.
6.
7.
8.
9.
Lips—several common patterns
Voice—electronic pulses measured on a spectrograph
Foot—size of foot and toes; friction ridges on the foot
Shoes—can be compared and identified by type of shoe, brand, size, year of purchase,
and wear pattern
Palm—friction ridges can be identified and may be used against suspects
Footprints are taken at birth as a means of identification of infants.
Ear-print
 A man has been convicted of suffocating an elderly woman on the basis of
ear-print evidence.
 The assailant was caught after police matched the imprint of his ear on the
victim’s window.
 Police believe that the thief put his ear to the window to listen for signs of
anyone home.
Teeth
 bite marks are unique and can be used to identify suspects.
 These imprints were placed in gum and could be matched to crime scene
evidence.
Blood vessel patterns
 Blood vessel patterns in the eye may be unique to individuals.
 They are used today for various security purposes.
AFIS
1. The Automated Fingerprint Identification System—a computer system for storing and
retrieving fingerprints
2. Established in the 1970s, AFIS enables law enforcement
officials to:
 Search large files for a set of prints taken from an individual
 Compare a single print, usually a latent print developed from a
crime scene
3. By the 1990s, most large jurisdictions had their own system in place. The problem: A
person’s fingerprints may be in one AFIS database but not in others.
4. IAFIS—the FBI’s Integrated Automated Fingerprint Identification System, which is a
national database of all 10-print cards from all over the country
Biometrics
1. Use of some type of body metrics for the purpose of identification. (The Bertillon system
may actually have been the first biometry system.)
2. Used today in conjunction with AFIS.
3. Examples include retinal or iris patterns, voice recognition, hand geometry.
4. Other functions for biometrics: can be used to control entry or access to computers or
other structures; can identify a person for security purposes; can help prevent identity
theft or control social services fraud.